Replace only the first instance of a substring in an NSString

Assuming the following inputs:

NSString *myString = @"My blue car is bigger then my blue shoes or my blue bicycle";
NSString *original = @"blue";
NSString *replacement = @"green";

The algorithm is quite simple:

NSRange rOriginal = [myString rangeOfString:original];

if (NSNotFound != rOriginal.location) {
    myString = [myString stringByReplacingCharactersInRange:rOriginal withString:replacement];
}